Water absorbing material and manufacturing method thereof

ABSTRACT

A water absorbing material includes a granular core portion and a coating layer portion. The coating layer portion covers the granular core portion. The coating layer portion contains fluff pulp and a water-absorbent polymer. These fluff pulp and water-absorbent polymer are both derived from a sanitary article.

CROSS REFERENCE TO RELATED APPLICATION

This is a Continuation of International Application No.PCT/JP2013/063179 filed May 10, 2013. The contents of this applicationare hereby incorporated by reference in their entirety.

TECHNICAL FIELD

The present invention relates to a water absorbing material that absorbsliquid such as excrement of humans or animals, and a manufacturingmethod of the water absorbing material.

BACKGROUND ART

Patent Document 1 describes an excrement treatment material that is atype of water absorbing material. In this excrement treatment material,a core portion and a surface layer portion that covers the core portionare provided. The surface layer portion has a function of causing theexcrement treatment materials, which absorbed liquid such as urine inuse, to adhere to each other so as to form an aggregate.

-   Patent Document 1: JP2006-333773A

SUMMARY OF INVENTION Technical Problem

The surface layer portion contains preferably an adhesive material inaddition to a water-absorbent material in order to have the function ofmaking an aggregate. Thus, a water absorbing material which is excellentboth in the function of absorbing water and in the function of making anaggregate is obtained. However, if the surface layer portion containsboth the water-absorbent material and the adhesive material, it causesincrease of procuring cost of raw materials and eventually increase ofmanufacturing cost of the water absorbing material.

Solution to Problem

The present invention was made in view of the above-described problems,and it is an object thereof to provide a water absorbing material whichis excellent in the function of absorbing water and in the function ofmaking an aggregate, and which can be manufactured at low cost, and amanufacturing method of the water absorbing material.

A water absorbing material according to the present invention includes acore portion and a surface layer portion that covers the core portion,wherein the surface layer portion contains fluff pulp and awater-absorbent polymer that are derived from a sanitary article.

In this water absorbing material, the surface layer portion containsfluff pulp and a water-absorbent polymer. The fluff pulp functions as awater-absorbent material, and the water-absorbent polymer functions asan adhesive material. These fluff pulp and water-absorbent polymer areboth derived from a sanitary article (disposable diaper, sanitarynapkin, urine absorbing pad, and so forth). Here, being derived from asanitary article refers to being produced in classification ormanufacture of the sanitary article.

Thus, it becomes possible to use fluff pulp and a water-absorbentmaterial that are separated from a waste sanitary article as rawmaterials of the surface layer portion. Also, it becomes possible to usefluff pulp and a water-absorbent material that are residues generated inmanufacture of a sanitary article as raw materials of the surface layerportion. Accordingly, it is possible to reduce procuring cost of rawmaterials and eventually reduce manufacturing cost of the waterabsorbing material.

A manufacturing method of a water absorbing material including a coreportion and a surface layer portion that covers the core portionaccording to the present invention includes an obtaining step ofobtaining fluff pulp and a water-absorbent polymer that are derived froma sanitary article, and a forming step of forming the surface layerportion using the fluff pulp and the water-absorbent polymer obtained inthe obtaining step as raw materials.

In this manufacturing method, fluff pulp and a water-absorbent polymerthat are derived from a sanitary article are used as raw materials ofthe surface layer portion. Thus, it becomes possible to use fluff pulpand a water-absorbent material that are separated from a waste sanitaryarticle as raw materials of the surface layer portion. Also, it becomespossible to use fluff pulp and a water-absorbent material that areresidues generated in manufacture of a sanitary article as raw materialsof the surface layer portion. Accordingly, it is possible to reduceprocuring cost of raw materials and eventually reduce manufacturing costof the water absorbing material.

Advantageous Effects of Invention

According to the present invention, a water absorbing material which isexcellent in the function of absorbing water and in the function ofmaking an aggregate, and which can be manufactured at low cost, and amanufacturing method of the water absorbing material are realized.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic view of an embodiment of a water absorbingmaterial according to the present invention.

FIG. 2 is a configuration diagram showing an embodiment of a separationdevice according to the present invention.

FIG. 3 is a side view showing a separation unit 40 of the separationdevice in FIG. 2.

FIG. 4 is a cross-sectional view taken along line IV-IV in FIG. 3.

FIG. 5 is a side view showing a separation unit 60 of the separationdevice in FIG. 2.

FIG. 6 is a cross-sectional view taken along line VI-VI in FIG. 5.

FIG. 7 is a cross-sectional view showing a transfer path 76 of theseparation device in FIG. 2.

FIG. 8 is a cross-sectional view showing a transfer path 78 of theseparation device in FIG. 2.

FIG. 9 is a cross-sectional view showing a transfer path 80 of theseparation device in FIG. 2.

FIG. 10 is a cross-sectional view for explaining a modification of aridge 44 shown in FIG. 4.

FIG. 11 is a cross-sectional view for explaining a modification of anuneven surface 77 a and an uneven surface 77 b shown in FIG. 7.

FIG. 12 is a cross-sectional view for explaining a modification of theuneven surface 77 a and the uneven surface 77 b shown in FIG. 7.

DESCRIPTION OF EMBODIMENTS

Hereinafter, embodiments of the present invention will be described indetail with reference to the drawings. It should be noted that thedescription of the drawings denotes like elements by like referencenumerals and omits redundant descriptions.

FIG. 1 is a schematic view of an embodiment of a water absorbingmaterial according to the present invention. A water absorbing material1 is an excrement treatment material for a pet animal such as cat anddog, and includes a granular core portion 10 (core portion) and acoating layer portion 20 (surface layer portion).

The coating layer portion 20 covers the granular core portion 10. Thecoating layer portion 20 may cover the entire surface of the granularcore portion 10, or may cover only a part of the surface of the granularcore portion 10. The coating layer portion 20 contains fluff pulp and awater-absorbent polymer (including a highly water-absorbent polymer; thesame shall apply hereinafter). These fluff pulp and water-absorbentpolymer are both derived from a sanitary article. The sanitary articleis, for example, disposable diaper, sanitary napkin, or urine absorbingpad. A waste sanitary article is preferably used as the sanitaryarticle. In the present embodiment, the fluff pulp and thewater-absorbent polymer are separated from the sanitary article with aseparation device mentioned later.

The fluff pulp is contained in the coating layer portion 20 as a mainmaterial, and the water-absorbent polymer is contained in the coatinglayer portion 20 as a sub material. Here, the main material refers tothe raw material whose weight ratio with respect to the coating layerportion 20 is the highest among all raw materials constituting thecoating layer portion 20. The sub material refers to the raw materialwhose weight ratio with respect to the coating layer portion 20 is thesecond highest among all raw materials constituting the coating layerportion 20.

FIG. 2 is a configuration diagram showing a separation device used inthe present embodiment. A separation device 90 processes a processingtarget containing a first material and a second material, therebydissociating the first and second materials from each other andseparating the second material from the processing target. In thepresent embodiment, the processing target is a sanitary article, thefirst material is plastic, and the second material is fluff pulp and awater-absorbent polymer. The separation device 90 includes a shreddingunit 30 (first shredding unit), a separation unit 40 (first separationunit), a shredding unit 50 (second shredding unit), and a separationunit 60 (second separation unit).

The shredding unit 30 shreds the sanitary article. For example, acrusher or a grinder can be used as the shredding unit 30. In the casewhere the sanitary article is a disposable diaper, for example, it ispreferable that no screen is provided in the shredding unit 30.

The structure of the separation unit 40 will be described with referenceto FIGS. 3 and 4. FIG. 3 is a side view showing the separation unit 40.FIG. 4 is a cross-sectional view taken along line IV-IV in FIG. 3. Theseparation unit 40 has a drum 42 (first tubular portion). The drum 42has a substantially cylindrical tubular shape and is provided so as tobe rotatable about its central axis. The central axis of the drum 42extends horizontally. The inner diameter of the drum 42 may be between30 cm and 50 cm inclusive, for example.

A large number of holes 42 a (first holes) are formed in the drum 42.The holes 42 a are formed over substantially the entire drum 42. Theholes 42 a do not allow plastic contained in the sanitary articleshredded by the shredding unit 30 to pass through, but allow the fluffpulp and the water-absorbent polymer to pass through. In the case wherethe sanitary article is a disposable diaper, for example, it ispreferable that the diameter of the holes 42 a is between 10 mm and 30mm inclusive. The separation unit 40 rotates the drum 42 in a state inwhich the sanitary article shredded by the shredding unit 30 isaccommodated therein, thereby separating the fluff pulp and thewater-absorbent polymer passing through the holes 42 a from the sanitaryarticle.

A ridge 44 (first ridge) is formed on an inner circumferential surfaceof the drum 42. The ridge 44 extends in a direction in which the centralaxis of the drum 42 extends. The ridge 44 extends over substantially theentire path from an inlet side (left side of FIG. 3) to an outlet side(right side of FIG. 3) of the drum 42. Also, the ridge 44 has asubstantially triangular cross-sectional shape. The height (length inthe radial direction of the drum 42) of the ridge 44 may be between 5 mmand 2 cm inclusive, for example. Preferably, “p” (p: an integer between3 and 5 inclusive) ridges 44 are provided. The “p” ridges 44 arearranged on the inner circumferential surface of the drum 42 at regularintervals. That is so say, in a cross section (cross section shown inFIG. 4) that is perpendicular to the central axis of the drum 42, anangle α that is formed by a line connecting one ridge 44 to the centralaxis and a line connecting the next ridge 44 to the central axis issubstantially equal to 360°/p. In the present embodiment, p=4 and α=90°.

A rotating rod 46 and a screw member 48 are provided inside the drum 42.The rotating rod 46 has a substantially cylindrical shape and isprovided so as to be rotatable about its central axis. The central axisof the rotating rod 46 coincides with the central axis of the drum 42.However, the rotating rod 46 rotates independently of the drum 42. Theouter diameter of the rotating rod 46 may be between 15 cm and 25 cminclusive, for example.

The screw member 48 is helically provided around the rotating rod 46.The screw member 48 is fixed to the rotating rod 46 and rotates togetherwith the rotating rod 46. A plurality of teeth 49 are formed in thescrew member 48. An end portion of each tooth 49 is constituted by aside 49 a and a side 49 b in a front view (see FIG. 4).

The side 49 a extends in the radial direction of the drum 42 and therotating rod 46. An inner end (end that is closer to the rotating rod46) of the side 49 a is located at a position spaced apart from therotating rod 46. Similarly, an outer end (end that is closer to the drum42) of the side 49 a is located at a position spaced apart from the drum42. The distance from the outer end of the side 49 a to the innercircumferential surface of the drum 42 is larger than the height of theridge 44 and may be between 1 cm and 3 cm inclusive, for example. Theside 49 b connects the outer end of the side 49 a to the inner end ofthe side 49 a of the next tooth 49. The side 49 b is longer than theside 49 a. The ratio of the length of the side 49 b to the length of theside 49 a may be between 2 and 2.5 inclusive, for example.

The rotating rod 46 and the screw member 48 rotate in a left-handeddirection (counterclockwise) in FIG. 4. That is to say, in each tooth49, the side 49 b is located on the forward side with respect to therotation direction, and the side 49 a is located on the rearward sidewith respect to the rotation direction. The rotation direction of thedrum 42 described above may be the same as the rotation direction of therotating rod 46 and the screw member 48 or may be opposite to thisrotation direction. In the case where these rotation directions are thesame, it is preferable that the rotation speed of the rotating rod 46and the screw member 48 is greater than the rotation speed of the drum42.

The shredding unit 50 shreds the sanitary article from which the fluffpulp and the water-absorbent polymer passing through the holes 42 a havebeen separated by the separation unit 40. For example, a crusher or agrinder can be used as the shredding unit 50. A screen is provided inthe shredding unit 50. In the case where the sanitary article is adisposable diaper, for example, it is preferable that the hole diameterof the screen is between 30 mm and 70 mm inclusive, for example.

The structure of the separation unit 60 will be described with referenceto FIGS. 5 and 6. FIG. 5 is a side view showing the separation unit 60.FIG. 6 is a cross-sectional view taken along line VI-VI in FIG. 5. Theseparation unit 60 has a drum 62 (second tubular portion). The drum 62has a substantially cylindrical tubular shape and is provided so as tobe rotatable about its central axis. The central axis of the drum 62extends horizontally. The inner diameter of the drum 62 may be between30 cm and 50 cm inclusive, for example.

A large number of holes 62 a (second holes) are formed in the drum 62.The holes 62 a are formed over substantially the entire drum 62. Theholes 62 a do not allow the plastic contained in the sanitary articleshredded by the shredding unit 50 to pass through, but allow the fluffpulp and the water-absorbent polymer to pass through. The area of eachof the holes 62 a in a plan view is smaller than the area of each of theholes 42 a in a plan view. In the case where the sanitary article is adisposable diaper, for example, it is preferable that the diameter ofthe holes 62 a is between 5 mm and 20 mm inclusive. The separation unit60 rotates the drum 62 in a state in which the sanitary article shreddedby the shredding unit 50 is accommodated therein, thereby separating thefluff pulp and the water-absorbent polymer passing through the holes 62a from the sanitary article.

A ridge 64 (second ridge) is formed on an inner circumferential surfaceof the drum 62. The ridge 64 extends in a direction in which the centralaxis of the drum 62 extends. The ridge 64 extends over substantially theentire path from an inlet side (left side of FIG. 5) to an outlet side(right side of FIG. 5) of the drum 62. Also, the ridge 64 has asubstantially triangular cross-sectional shape. The height (length inthe radial direction of the drum 62) of the ridge 64 may be between 5 mmand 2 cm inclusive, for example. Preferably, “q” (q: an integer between3 and 5 inclusive) ridges 64 are provided. The “q” ridges 64 arearranged on the inner circumferential surface of the drum 62 at regularintervals. That is to say, in a cross section (cross section shown inFIG. 6) that is perpendicular to the central axis of the drum 62, anangle β that is formed by a line connecting one ridge 64 to the centralaxis and a line connecting the next ridge 64 to the central axis issubstantially equal to 360°/q. In the present embodiment, q=4 and β=90°.

A rotating rod 66 and a screw member 68 are provided inside the drum 62.The rotating rod 66 has a substantially cylindrical shape and isprovided so as to be rotatable about its central axis. The central axisof the rotating rod 66 coincides with the central axis of the drum 62.However, the rotating rod 66 rotates independently of the drum 62. Theouter diameter of the rotating rod 66 may be between 15 cm and 25 cminclusive, for example.

The screw member 68 is helically provided around the rotating rod 66.The screw member 68 is fixed to the rotating rod 66 and rotates togetherwith the rotating rod 66. A plurality of teeth 69 are formed in thescrew member 68. An end portion of each tooth 69 is constituted by aside 69 a and a side 69 b in a front view (see FIG. 6).

The side 69 a extends in the radial direction of the drum 62 and therotating rod 66. An inner end (end that is closer to the rotating rod66) of the side 69 a is located at a position spaced apart from therotating rod 66. Similarly, an outer end (end that is closer to the drum62) of the side 69 a is located at a position spaced apart from the drum62. The distance from the outer end of the side 69 a to the innercircumferential surface of the drum 62 is larger than the height of theridge 64 and may be between 1 cm and 3 cm inclusive, for example. Theside 69 b connects the outer end of the side 69 a to the inner end ofthe side 69 a of the next tooth 69. The side 69 b is longer than theside 69 a. The ratio of the length of the side 69 b to the length of theside 69 a may be between 2 and 2.5 inclusive, for example.

The rotating rod 66 and the screw member 68 rotate in a left-handeddirection (counterclockwise) in FIG. 6. That is to say, in each tooth69, the side 69 b is located on the forward side with respect to therotation direction, and the side 69 a is located on the rearward sidewith respect to the rotation direction. The rotation direction of thedrum 62 described above may be the same as the rotation direction of therotating rod 66 and the screw member 68 or may be opposite to thisrotation direction. In the case where these rotation directions are thesame, it is preferable that the rotation speed of the rotating rod 66and the screw member 68 is greater than the rotation speed of the drum62.

The separation device 90 is further provided with a transfer path 76, atransfer path 78, and a transfer path 80 (see FIG. 2). The transfer path76 is a duct (first air pipe) and transfers the sanitary article aftershredding by the shredding unit 30 to the separation unit 40 with airpressure. The transfer path 78 is a duct (second air pipe) and transfersthe sanitary article after separation by the separation unit 40 to theshredding unit 50 with air pressure. The transfer path 80 is a duct(third air pipe) and transfers the sanitary article after shredding bythe shredding unit 50 to the separation unit 60.

The structure of the transfer path 76 will be described with referenceto FIG. 7. FIG. 7 is a cross-sectional view showing the transfer path76. The transfer path 76 has a portion 76 a (first portion) extending ina first direction, a portion 76 b (second portion) extending in a seconddirection, and a portion 76 c (third portion) extending in a thirddirection. In the present embodiment, the first direction is ahorizontal direction, the second direction is a vertical direction, andthe third direction is a horizontal direction. The portion 76 b isconnected to the portion 76 a on a downstream side of the portion 76 a.The portion 76 c is connected to the portion 76 b on the downstream sideof the portion 76 b. Thus, the portion 76 a, the portion 76 b, and theportion 76 c constitute a single cranked duct. The inner diameter of thetransfer path 76 may be between 10 cm and 20 cm inclusive, for example.

An uneven surface 77 a (first uneven surface) is present in a connectingportion between the portion 76 a and the portion 76 b. The unevensurface 77 a is provided at a position where the sanitary article thatis transferred through the portion 76 a collides with this unevensurface. The uneven surface 77 a is at an angle of about 45° to avertical plane. For example, a corrugated or embossed plate-like membercan be used as the uneven surface 77 a. The material for the unevensurface 77 a may be aluminum, for example.

An uneven surface 77 b (second uneven surface) is present in aconnecting portion between the portion 76 b and the portion 76 c. Theuneven surface 77 b is provided at a position where the sanitary articlethat is transferred through the portion 76 b collides with this unevensurface. The uneven surface 77 b is at an angle of about 45° to ahorizontal plane. For example, a corrugated or embossed plate-likemember can be used as the uneven surface 77 b. The material for theuneven surface 77 b may be aluminum, for example.

The structure of the transfer path 78 will be described with referenceto FIG. 8. FIG. 8 is a cross-sectional view showing the transfer path78. The transfer path 78 has a portion 78 a (first portion) extending ina first direction, a portion 78 b (second portion) extending in a seconddirection, and a portion 78 c (third portion) extending in a thirddirection. In the present embodiment, the first direction is ahorizontal direction, the second direction is a vertical direction, andthe third direction is a horizontal direction. The portion 78 b isconnected to the portion 78 a on the downstream side of the portion 78a. The portion 78 c is connected to the portion 78 b on the downstreamside of the portion 78 b. Thus, the portion 78 a, the portion 78 b, andthe portion 78 c constitute a single cranked duct. The inner diameter ofthe transfer path 78 may be between 10 cm and 20 cm inclusive, forexample.

An uneven surface 79 a (third uneven surface) is present in a connectingportion between the portion 78 a and the portion 78 b. The unevensurface 79 a is provided at a position where the sanitary article thatis transferred through the portion 78 a collides with this unevensurface. The uneven surface 79 a is at an angle of about 45° to avertical plane. For example, a corrugated or embossed plate-like membercan be used as the uneven surface 79 a. The material for the unevensurface 79 a may be aluminum, for example.

An uneven surface 79 b (fourth uneven surface) is present in aconnecting portion between the portion 78 b and the portion 78 c. Theuneven surface 79 b is provided at a position where the sanitary articlethat is transferred through the portion 78 b collides with this unevensurface. The uneven surface 79 b is at an angle of about 45° to ahorizontal plane. For example, a corrugated or embossed plate-likemember can be used as the uneven surface 79 b. The material for theuneven surface 79 b may be aluminum, for example.

The structure of the transfer path 80 will be described with referenceto FIG. 9. FIG. 9 is a cross-sectional view showing the transfer path80. The transfer path 80 has a portion 80 a (first portion) extending ina first direction, a portion 80 b (second portion) extending in a seconddirection, and a portion 80 c (third portion) extending in a thirddirection. In the present embodiment, the first direction is ahorizontal direction, the second direction is a vertical direction, andthe third direction is a horizontal direction. The portion 80 b isconnected to the portion 80 a on the downstream side of the portion 80a. The portion 80 c is connected to the portion 80 b on the downstreamside of the portion 80 b. Thus, the portion 80 a, the portion 80 b, andthe portion 80 c constitute a single cranked duct. The inner diameter ofthe transfer path 80 may be between 10 cm and 20 cm inclusive, forexample.

An uneven surface 81 a (fifth uneven surface) is present in a connectingportion between the portion 80 a and the portion 80 b. The unevensurface 81 a is provided at a position where the sanitary article thatis transferred through the portion 80 a collides with this unevensurface. The uneven surface 81 a is at an angle of about 45° to avertical plane. For example, a corrugated or embossed plate-like membercan be used as the uneven surface 81 a. The material for the unevensurface 81 a may be aluminum, for example.

An uneven surface 81 b (sixth uneven surface) is present in a connectingportion between the portion 80 b and the portion 80 c. The unevensurface 81 b is provided at a position where the sanitary article thatis transferred through the portion 80 b collides with this unevensurface. The uneven surface 81 b is at an angle of about 45° to ahorizontal plane. For example, a corrugated or embossed plate-likemember can be used as the uneven surface 81 b. The material for theuneven surface 81 b may be aluminum, for example.

The operation of the separation device 90 will be described. A sanitaryarticle, which is a processing target, is first shredded by theshredding unit 30. The sanitary article shredded by the shredding unit30 is transferred to the separation unit 40 through the transfer path76. The sanitary article transferred to the separation unit 40 ispropelled from the inlet side (left side of FIG, 3) to the outlet side(right side of FIG. 3) of the drum 42 by the rotating screw member 48.Meanwhile, due to the centrifugal force and the like generated by therotation of the drum 42, the fluff pulp and the water-absorbent polymerdissociated from the plastic are discharged to the outside of the drum42 through the holes 42 a. Thus, a portion of the fluff pulp and aportion of the water-absorbent polymer are separated from the sanitaryarticle, and they can be used as raw materials of the coating layerportion 20.

The sanitary article after separation by the separation unit 40 istransferred to the shredding unit 50 through the transfer path 78 and isfurther shredded. The sanitary article shredded by the shredding unit 50is transferred to the separation unit 60 through the transfer path 80.The sanitary article transferred to the separation unit 60 is propelledfrom the inlet side (left side of FIG. 5) to the outlet side (right sideof FIG. 5) of the drum 62 by the rotating screw member 68. Meanwhile,due to the centrifugal force and the like generated by the rotation ofthe drum 62, the fluff pulp and the water-absorbent polymer dissociatedfrom the plastic are discharged to the outside of the drum 62 throughthe holes 62 a. Thus, the remaining fluff pulp and water-absorbentpolymer are separated from the sanitary article, and they also can beused as raw materials of the coating layer portion 20.

An example of a manufacturing method of the water absorbing material 1will be described as an embodiment of a manufacturing method of a waterabsorbing material according to the present invention. Thismanufacturing method includes an obtaining step, a fluff pulverizingstep, a polymer pulverizing step, a granulating step, a coating step(forming step), a classification step, and a drying step.

The obtaining step is a step of obtaining fluff pulp and awater-absorbent polymer that are derived from a sanitary article. In thepresent embodiment, these materials are obtained by being separated fromthe sanitary article.

In the obtaining step, the separation device 90 described above is used.That is, in the obtaining step, a sanitary article is first shredded bythe shredding unit 30 (first shredding step). Next, the drum 42 isrotated in a state in which the sanitary article shredded by theshredding unit 30 is accommodated therein, and thereby the fluff pulpand the water-absorbent polymer passing through the holes 42 a areseparated from the sanitary article in the separation unit 40 (firstseparating step).

After that, the sanitary article from which the fluff pulp and thewater-absorbent polymer are separated in the first separating step isfurther shredded by the shredding unit 50 (second shredding step). Next,the drum 62 is rotated in a state in which the sanitary article shreddedby the shredding unit 50 is accommodated therein, and thereby the fluffpulp and the water-absorbent polymer passing through the holes 62 a areseparated from the sanitary article in the separation unit 60 (secondseparating step).

The fluff pulverizing step is a step of pulverizing the fluff pulpobtained in the obtaining step with a grinder that has a screen a holediameter of which is 0.5 mm or less (preferably 0.3 mm or less). Thepolymer pulverizing step is a step of pulverizing the water-absorbentpolymer obtained in the obtaining step such that the water-absorbentpolymer has a grain size of 50 μm or less (preferably 25 μm or less). Itshould be noted that the fluff pulverizing step and the polymerpulverizing step may be omitted. The granulating step is a step offorming the granular core portion 10. In this step, a core portionmaterial (material that constitutes the granular core portion 10) issubjected to extrusion granulation using a granulator after adding waterthereto. As the core portion material, for example, papers, fibers,woods, plants, plastics, rubbers, or organic sludge can be used. Theymay be used in combination of two or more. Thus, the granular coreportion 10 is formed.

The coating step is a step of forming the coating layer portion 20. Inthis step, a coating material (material that constitutes the coatinglayer portion 20) is stuck to the surface of the granular core portion10 using a coating device and the like. Sticking of the coating materialmay be performed by, for example, sprinkling or spraying. Thus, thecoating layer portion 20 is formed.

The coating material contains the fluff pulp pulverized in the fluffpulverizing step and the water-absorbent polymer pulverized in thepolymer pulverizing step. Fluff pulp and a water-absorbent polymer usedin the coating material may be those obtained in either of the firstseparating step or the second separating step, or may be those obtainedin both of the first and second separating steps. The coating materialmay consist only of the fluff pulp and the water-absorbent polymer, ormay consist of a mixture of these materials and other materials.

In the classification step, only the water absorbing materials that meeta predetermined standard are obtained by sifting the water absorbingmaterials manufactured in the preceding step with a sieve having apredetermined mesh size.

In the drying step, the water absorbing materials obtained in thepreceding step are dried by a dryer. By appropriately adjusting themoisture content of the granular core portion 10, it is possible toprevent degradation of water absorbing performance caused by movement ofwater from the granular core portion 10 to the coating layer portion 20,and to prevent the growth of mold and the like during storage of thewater absorbing material 1. Accordingly, the water absorbing material 1is obtained.

The effects of the present embodiment will be described. In the presentembodiment, the coating layer portion 20 contains fluff pulp and awater-absorbent polymer. The fluff pulp functions as a water-absorbentmaterial, and the water-absorbent polymer functions as an adhesivematerial. These fluff pulp and water-absorbent polymer are both producedin classification of a sanitary article.

Thus, it becomes possible to use fluff pulp and a water-absorbentmaterial that are separated from a waste sanitary article as rawmaterials of the coating layer portion 20. Accordingly, it is possibleto reduce procuring cost of raw materials and eventually reducemanufacturing cost of the water absorbing material 1. Consequently, thewater absorbing material 1 which is excellent in the function ofabsorbing water and in the function of making an aggregate, and whichcan be manufactured at low cost, and the manufacturing method thereofare realized.

In particular, the fluff pulp and the water-absorbent material arecontained in the coating layer portion 20 as, respectively, the mainmaterial and the sub material. Thus, the effect of reducing procuringcost of raw materials is remarkably exhibited.

In the present embodiment, after shredding by the shredding unit 30 andseparation by the separation unit 40, shredding by the shredding unit 50and separation by the separation unit 60 are performed. Therefore, theseparation efficiency is improved when compared with the case whereshredding and separation are performed only one time. Here, theseparation efficiency refers to the ratio of the weight of the secondmaterial that is separated from the processing target to the weight ofthe second material that is contained in the processing targetimmediately before the processing.

The drum 42 is provided with the ridges 44. If the ridges 44 are notprovided, the sanitary article tends to collect in a lower portion ofthe drum 42 due to the effect of gravity. In contrast, in the presentembodiment, the sanitary article in the drum 42 is scooped up by theridges 44 and thus easily reaches an upper portion of the drum 42.Therefore, the sanitary article is distributed over a wide range of theinner circumferential surface of the drum 42, so that separation by theseparation unit 40 is promoted. Moreover, dissociation of the fluff pulpand the water-absorbent material from the plastic is promoted by theimpact of the sanitary article when falling down from the upper portionof the drum 42. Furthermore, the ridges 44 become obstacles when thesanitary article is propelled by the screw member 48, and thus the timefor which the sanitary article stays in the drum 42 is prolonged. Thus,a larger amount of fluff pulp and water-absorbent material can beseparated from the sanitary article.

The screw member 48 is provided inside the drum 42. The sanitary articlein the drum 42 is beaten and rubbed against the inner circumferentialsurface of the drum 42 by the screw member 48. The impact and thefrictional force at that time promote dissociation of the fluff pulp andthe water-absorbent material from the plastic. Moreover, since theridges 44 are provided, the sanitary article may be beaten and rubbedagainst the inner circumferential surface of the drum 42 by the screwmember 48 in a state in which the sanitary article is caught on theridges 44. In that case, forces are focused, so that the impact and thefrictional force that are applied to the sanitary article increase, andaccordingly dissociation of the fluff pulp and the water-absorbentmaterial from the plastic is promoted even more.

The screw member 48 rotates with the side 49 b that forms an obtuseangle with the rotation direction (direction of the tangent to therotating rod 46), rather than the side 49 a that forms an approximatelyright angle with the rotation direction, being located on the forwardside (see FIG. 4). Thus, the sanitary article can be prevented frombeing excessively caught on the teeth 49 of the screw member 48.

The drum 62 is provided with the ridges 64. If the ridges 64 are notprovided, the sanitary article tends to collect in a lower portion ofthe drum 62 due to the effect of gravity. In contrast, in the presentembodiment, the sanitary article in the drum 62 is scooped up by theridges 64 and thus easily reaches an upper portion of the drum 62.Therefore, the sanitary article is distributed over a wide range of theinner circumferential surface of the drum 62, so that separation by theseparation unit 60 is promoted. Moreover, dissociation of the fluff pulpand the water-absorbent material from the plastic is promoted by theimpact of the sanitary article when falling down from the upper portionof the drum 62. Furthermore, the ridges 64 become obstacles when thesanitary article is propelled by the screw member 68, and thus the timefor which the sanitary article stays in the drum 62 is prolonged. Thus,a larger amount of fluff pulp and water-absorbent material can beseparated from the sanitary article.

The screw member 68 is provided inside the drum 62. The sanitary articlein the drum 62 is beaten and rubbed against the inner circumferentialsurface of the drum 62 by the screw member 68. The impact and thefrictional force at that time promote dissociation of the fluff pulp andthe water-absorbent material from the plastic. Moreover, since theridges 64 are provided, the sanitary article may be beaten and rubbedagainst the inner circumferential surface of the drum 62 by the screwmember 68 in a state in which the sanitary article is caught on theridges 64. In that case, forces are focused, so that the impact and thefrictional force that are applied to the sanitary article increase, andaccordingly dissociation of the fluff pulp and the water-absorbentmaterial from the plastic is promoted even more.

The screw member 68 rotates with the side 69 b that forms an obtuseangle with the rotation direction (direction of the tangent to therotating rod 66), rather than the side 69 a that forms an approximatelyright angle with the rotation direction, being located on the forwardside (see FIG. 6). Thus, the sanitary article can be prevented frombeing excessively caught on the teeth 69 of the screw member 68.

The transfer path 76 has the portion 76 a and the portion 76 b that areorthogonal to each other (see FIG. 7). Thus, the sanitary articletransferred by air pressure collides with the inner surface of thetransfer path 76 in the connecting portion between the portion 76 a andthe portion 76 b. The impact of this collision promotes dissociation ofthe fluff pulp and the water-absorbent material from the plastic.Furthermore, the transfer path 76 has the portion 76 c that isorthogonal to the portion 76 b. Thus, the sanitary article transferredby air pressure also collides with the inner surface of the transferpath 76 in the connecting portion between the portion 76 b and theportion 76 c. The impact of this collision promotes dissociation of thefluff pulp and the water-absorbent material from the plastic.

The uneven surface 77 a is present in the connecting portion between theportion 76 a and the portion 76 b. When colliding with the unevensurface 77 a, the sanitary article is subjected to a stronger impactthan in the case where it collides with a flat surface. Therefore,dissociation of the fluff pulp and the water-absorbent material from theplastic is promoted even more. Furthermore, the uneven surface 77 b ispresent in the connecting portion between the portion 76 b and theportion 76 c. When colliding with the uneven surface 77 b, the sanitaryarticle is subjected to a stronger impact than in the case where itcollides with a flat surface. Therefore, dissociation of the fluff pulpand the water-absorbent material from the plastic is promoted even more.

The transfer path 78 has the portion 78 a and the portion 78 b that areorthogonal to each other (see FIG. 8). Thus, the sanitary articletransferred by air pressure collides with the inner surface of thetransfer path 78 in the connecting portion between the portion 78 a andthe portion 78 b. The impact of this collision promotes dissociation ofthe fluff pulp and the water-absorbent material from the plastic.Furthermore, the transfer path 78 has the portion 78 c that isorthogonal to the portion 78 b. Thus, the sanitary article transferredby air pressure also collides with the inner surface of the transferpath 78 in the connecting portion between the portion 78 b and theportion 78 c. The impact of this collision promotes dissociation of thefluff pulp and the water-absorbent material from the plastic.

The uneven surface 79 a is present in the connecting portion between theportion 78 a and the portion 78 b. When colliding with the unevensurface 79 a, the sanitary article is subjected to a stronger impactthan in the case where it collides with a flat surface. Therefore,dissociation of the fluff pulp and the water-absorbent material from theplastic is promoted even more. Furthermore, the uneven surface 79 b ispresent in the connecting portion between the portion 78 b and theportion 78 c. When colliding with the uneven surface 79 b, the sanitaryarticle is subjected to a stronger impact than in the case where itcollides with a flat surface. Therefore, dissociation of the fluff pulpand the water-absorbent material from the plastic is promoted even more.

The transfer path 80 has the portion 80 a and the portion 80 b that areorthogonal to each other (see FIG. 9). Thus, the sanitary articletransferred by air pressure collides with the inner surface of thetransfer path 80 in the connecting portion between the portion 80 a andthe portion 80 b. The impact of this collision promotes dissociation ofthe fluff pulp and the water-absorbent material from the plastic.Furthermore, the transfer path 80 has the portion 80 c that isorthogonal to the portion 80 b. Thus, the sanitary article transferredby air pressure also collides with the inner surface of the transferpath 80 in the connecting portion between the portion 80 b and theportion 80 c. The impact of this collision promotes dissociation of thefluff pulp and the water-absorbent material from the plastic.

The uneven surface 81 a is present in the connecting portion between theportion 80 a and the portion 80 b. When colliding with the unevensurface 81 a, the sanitary article is subjected to a stronger impactthan in the case where it collides with a flat surface. Therefore,dissociation of the fluff pulp and the water-absorbent material from theplastic is promoted even more. Furthermore, the uneven surface 81 b ispresent in the connecting portion between the portion 80 b and theportion 80 c. When colliding with the uneven surface 81 b, the sanitaryarticle is subjected to a stronger impact than in the case where itcollides with a flat surface. Therefore, dissociation of the fluff pulpand the water-absorbent material from the plastic is promoted even more.

The water absorbing material and the manufacturing method thereofaccording to the present invention are not limited to the foregoingembodiments, and various modifications can be made thereto. For example,in the foregoing embodiments, an example in which fluff pulp and awater-absorbent material derived from a sanitary article are containedin the coating layer portion 20 as, respectively, the main material andthe sub material has been described. However, the fluff pulp is notnecessarily contained as the main material and the water-absorbentmaterial is not necessarily contained as the sub material as long asthey are contained in the coating layer portion 20.

In the foregoing embodiments, an example in which shredding andseparation are performed two times has been described. However, it isalso possible that shredding and separation are performed only one time,or three times or more.

In the foregoing embodiments, an example in which the drum 42 has acylindrical tubular shape has been described. However, it is alsopossible that the drum 42 has a tapered shape. The same applies to thedrum 62.

In the foregoing embodiments, an example in which the central axis ofthe drum 42 extends horizontally has been described. However, it is alsopossible that the central axis of the drum 42 is sloped downward fromthe inlet side toward the outlet side. The same applies to the drum 62.

In the foregoing embodiments, an example in which the holes 42 a areformed over substantially the entire drum 42 has been described.However, it is also possible that the holes 42 a are formed in only aportion of the drum 42. Moreover, it is also possible that the holes 42a are formed by forming substantially the whole or a portion of the drum42 in a mesh form. That is to say, in this case, the meshes of the drum42 correspond to the holes 42 a. The same applies to the holes 62 a.

In the foregoing embodiments, an example in which the ridges 44 extendover the entire path from the inlet side to the outlet side of the drum42 has been described. However, it is also possible that the ridges 44extend in only a portion of the path from the inlet side to the outletside of the drum 42. The same applies to the ridges 64.

In the foregoing embodiments, the ridges 44 having a substantiallytriangular cross-sectional shape have been described as an example.However, it is also possible that the ridges 44 have a flat plate-likeshape as shown in FIG. 10. The same applies to the ridges 64.

In the foregoing embodiments, an example in which four ridges 44 areprovided on the inner circumferential surface of the drum 42 has beendescribed. However, the number of ridges 44 can be set at any numbergreater than or equal to 1. The same applies to the ridges 64.

In the foregoing embodiments, an example in which the ridges 44 areprovided on the inner circumferential surface of the drum 42 has beendescribed. However, the provision of the ridges 44 is not necessarilyrequired. The same applies to the ridges 64.

In the foregoing embodiments, an example in which the rotating rod 46and the screw member 48 are provided inside the drum 42 has beendescribed. However, the provision of the rotating rod 46 and the screwmember 48 is not necessarily required. The same applies to the rotatingrod 66 and the screw member 68.

In the foregoing embodiments, an example in which the uneven surface 77a is at a certain angle to a vertical plane has been described. However,it is also possible that the uneven surface 77 a extends along avertical plane as shown in FIG. 11. Moreover, it is also possible thatthe uneven surface 77 a is realized by providing a protrusion P1 on theinner surface (position with which the sanitary article transferredthrough the portion 76 a collides) of the transfer path 76 as shown inFIG. 12. The number of protrusions P1 may be one or may be two or more.The same applies to the uneven surface 79 a and the uneven surface 81 a.

In the foregoing embodiments, an example in which the uneven surface 77b is at a certain angle to a horizontal plane has been described.

However, it is also possible that the uneven surface 77 b extends alonga horizontal plane as shown in FIG. 11. Moreover, it is also possiblethat the uneven surface 77 b is realized by providing a protrusion P2 onthe inner surface (position with which the sanitary article transferredthrough the portion 76 b collides) of the transfer path 76 as shown inFIG. 12. The number of protrusions P2 may be one or may be two or more.The same applies to the uneven surface 79 b and the uneven surface 81 b.

In the foregoing embodiments, an example in which the uneven surface 77a is provided has been described. However, the provision of the unevensurface 77 a is not necessarily required. The same applies to the unevensurface 79 a and the uneven surface 81 a.

In the foregoing embodiments, an example in which the uneven surface 77b is provided has been described. However, the provision of the unevensurface 77 b is not necessarily required. The same applies to the unevensurface 79 b and the uneven surface 81 b.

In the foregoing embodiment, an example in which the transfer path 76 isconstituted by a plurality of portions that are orthogonal to each otherhas been described (see FIG. 7). However, the transfer path 76 may be astraight line-shaped duct. The same applies to the transfer path 78 andthe transfer path 80.

In the foregoing embodiment, an example in which the fluff pulp and thewater-absorbent material are separated from the sanitary article by theseparation device 90 has been described. However, separation of thefluff pulp and the water-absorbent material from the sanitary articlemay be performed by other devices or methods.

In the foregoing embodiment, an example in which the fluff pulp and thewater-absorbent polymer that are produced in classification of thesanitary article are used as raw materials of the coating layer portion20 has been described. However, as the fluff pulp and thewater-absorbent polymer, those produced in manufacture of the sanitaryarticle may be used. Furthermore, a water-absorbent polymer that isseparated from the fluff pulp produced in manufacture of the sanitaryarticle may be used as raw materials of the coating layer portion 20. Inthis case, the water-absorbent polymer adheres to the fluff pulp, andthe weight ratio of the water-absorbent polymer adhering to the fluffpulp with respect to the fluff pulp is preferably 3% or less.

In the foregoing embodiment, an example in which the water absorbingmaterial is a granular excrement treatment material has been described.However, a water absorbing material according to the present inventionmay be a pet sheet, water stop material, water absorbing sheet, and soforth.

LIST OF REFERENCE NUMERALS

-   1 Water absorbing material-   10 Granular core portion-   20 Coating layer portion-   30 Shredding unit (first shredding unit)-   40 Separation unit (first separation unit)-   42 Drum (first tubular portion)-   42 a Hole (first hole)-   44 Ridge (first ridge)-   46 Rotating rod-   48 Screw member-   49 Tooth-   50 Shredding unit (second shredding unit)-   60 Separation unit (second separation unit)-   62 Drum (second tubular portion)-   62 a Hole (second hole)-   64 Ridge (second ridge)-   66 Rotating rod-   68 Screw member-   69 Tooth-   76 Transfer path (first air pipe)-   77 a Uneven surface (first uneven surface)-   77 b Uneven surface (second uneven surface)-   78 Transfer path (second air pipe)-   79 a Uneven surface (third uneven surface)-   79 b Uneven surface (fourth uneven surface)-   80 Transfer path (third air pipe)-   81 a Uneven surface (fifth uneven surface)-   81 b Uneven surface (sixth uneven surface)-   90 Separation device

1. A water absorbing material comprising a core portion and a surfacelayer portion that covers the core portion, wherein the surface layerportion contains fluff pulp and a water-absorbent polymer that arederived from a sanitary article.
 2. The water absorbing materialaccording to claim 1, wherein the fluff pulp and the water-absorbentpolymer are separated from the sanitary article with a separationdevice, and the separation device includes: a first shredding unit thatshreds the sanitary article; and a first separation unit that has afirst tubular portion in which a large number of first holes that allowthe fluff pulp and the water-absorbent polymer to pass through withoutallowing plastic contained in the sanitary article shredded by the firstshredding unit to pass through are formed, and that separates the fluffpulp and the water-absorbent polymer passing through the first holesfrom the sanitary article by rotating the first tubular portion in astate in which the sanitary article shredded by the first shredding unitis accommodated in the first tubular portion.
 3. The water absorbingmaterial according to claim 2, wherein the separation device includes afirst ridge that is provided on an inner circumferential surface of thefirst tubular portion and that extends in a direction in which a centralaxis of the first tubular portion extends.
 4. The water absorbingmaterial according to claim 3, wherein “p” of said first ridges arepresent, “p” being an integer between 3 and 5 inclusive, and the “p”first ridges are arranged on the inner circumferential surface of thefirst tubular portion at regular intervals.
 5. The water absorbingmaterial according to claim 2, wherein the separation device includes afirst air pipe for transferring the sanitary article shredded by thefirst shredding unit to the first separation unit with air pressure, andthe first air pipe has a first portion that extends in a first directionand a second portion that is connected to the first portion on adownstream side of the first portion and that extends in a seconddirection substantially orthogonal to the first direction.
 6. The waterabsorbing material according to claim 5, wherein the separation deviceincludes a first uneven surface that is present in a connecting portionbetween the first portion and the second portion of the first air pipeand with which the sanitary article transferred through the firstportion collides.
 7. The water absorbing material according to claim 5,wherein the first air pipe has a third portion that is connected to thesecond portion on a downstream side of the second portion and thatextends in a third direction substantially orthogonal to the seconddirection.
 8. The water absorbing material according to claim 7, whereinthe separation device includes a second uneven surface that is presentin a connecting portion between the second portion and the third portionof the first air pipe and with which the sanitary article transferredthrough the second portion collides.
 9. The water absorbing materialaccording to claims 2, wherein the separation device includes: a secondshredding unit that shreds the sanitary article from which the fluffpulp and the water-absorbent polymer passing through the first holes areseparated by the first separation unit; and a second separation unitthat has a second tubular portion in which a large number of secondholes that allow the fluff pulp and the water-absorbent polymer to passthrough without allowing the plastic contained in the sanitary articleshredded by the second shredding unit to pass through are formed, andthat separates the fluff pulp and the water-absorbent polymer passingthrough the second holes from the sanitary article by rotating thesecond tubular portion in a state in which the sanitary article shreddedby the second shredding unit is accommodated in the second tubularportion.
 10. The water absorbing material according to claim 9, whereinan area of each of the second holes in a plan view is smaller than anarea of each of the first holes in a plan view.
 11. The water absorbingmaterial according to claim 1, wherein the fluff pulp is fluff pulp thatis produced in manufacture of the sanitary article.
 12. The waterabsorbing material according to claim 11, wherein the water-absorbentpolymer is separated from the fluff pulp that is produced in manufactureof the sanitary article.
 13. The water absorbing material according toclaim 12, wherein the water-absorbent polymer adheres to the fluff pulp,and a weight ratio of the water-absorbent polymer adhering to the fluffpulp with respect to the fluff pulp is 3% or less.
 14. The waterabsorbing material according to claim 1, wherein the fluff pulp ispulverized with a grinder that has a screen a hole diameter of which is0.5 mm or less.
 15. The water absorbing material according to claim 1,wherein the water-absorbent polymer is pulverized so as to have a grainsize of 50 μm or less.
 16. The water absorbing material according toclaim 1, wherein the fluff pulp is contained in the surface layerportion as a main material, and the water-absorbent polymer is containedin the surface layer portion as a sub material.
 17. A manufacturingmethod of a water absorbing material including a core portion and asurface layer portion that covers the core portion comprising: anobtaining step of obtaining fluff pulp and a water-absorbent polymerthat are derived from a sanitary article; and a forming step of formingthe surface layer portion using the fluff pulp and the water-absorbentpolymer obtained in the obtaining step as raw materials.
 18. Themanufacturing method of the water absorbing material according to claim17, wherein the obtaining step includes: a first shredding step ofshredding the sanitary article; and a first separating step of rotatinga first tubular portion in which a large number of first holes thatallow the fluff pulp and the water-absorbent polymer to pass throughwithout allowing plastic contained in the sanitary article shredded inthe first shredding step to pass through are formed, the first tubularportion being rotated in a state in which the sanitary article shreddedin the first shredding step is accommodated in the first tubularportion, thereby separating the fluff pulp and the water-absorbentpolymer passing through the first holes from the sanitary article. 19.The manufacturing method of the water absorbing material according toclaim 18, wherein the obtaining step includes: a second shredding stepof shredding the sanitary article from which the fluff pulp and thewater-absorbent polymer passing through the first holes are separated inthe first separating step; and a second separating step of rotating asecond tubular portion in which a large number of second holes thatallow the fluff pulp and the water-absorbent polymer to pass throughwithout allowing the plastic contained in the sanitary article shreddedin the second shredding step to pass through are formed, the secondtubular portion being rotated in a state in which the sanitary articleshredded in the second shredding step is accommodated in the secondtubular portion, thereby separating the fluff pulp and thewater-absorbent polymer passing through the second holes from thesanitary article.
 20. The manufacturing method of the water absorbingmaterial according to claim 17, wherein in the obtaining step, as thefluff pulp, fluff pulp produced in manufacture of the sanitary articleis obtained.